216
FXUS63 KGRR 040606
AFDGRR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
206 AM EDT SAT APR 4 2026
KEY MESSAGES
- SHOWERS AND THUNDERSTORMS TONIGHT INTO SATURDAY
- TURNING COLDER FROM SUNDAY TO TUESDAY
- RAINY PATTERN RETURNS LATTER HALF OF NEXT WEEK
DISCUSSION
ISSUED AT 204 PM EDT FRI APR 3 2026
- SHOWERS AND THUNDERSTORMS TONIGHT INTO SATURDAY
CLUSTERS OF THUNDERSTORMS ARE EXPECTED TO DEVELOP AROUND/AFTER
MIDNIGHT AND PERSIST INTO PART OF SATURDAY MORNING. THESE STORMS
WILL BE DEVELOPING WITH INCREASING MOISTURE AND CONVERGENCE ON THE
NOSE OF AN 850 MB JET ALONG AN ELEVATED WARM FRONTAL SURFACE.
SEVERAL HUNDRED J/KG OF MUCAPE IS EXPECTED BUT UP TO 1000 IS
POSSIBLE. CAN'T RULE OUT SOME STORM CELLS PRODUCING HAIL GIVEN
INSTABILITY EXTENDING THROUGH -10 TO -20 C AIR. SHEAR ABOVE 1 KM
(THE EFFECTIVE INFLOW LAYER TONIGHT) IS A LITTLE JUNKY BUT THERE
IS SOME, PERHAPS CAN ALSO AID SOME CELLS IN THE PRODUCTION OF
HAIL. ALSO HAVE TO ADD THAT A LITTLE FREEZING RAIN IS POSSIBLE IN
THE HIGHEST ELEVATIONS OF NORTHERN OSCEOLA AND CLARE COUNTIES
PRIOR TO DAYBREAK SATURDAY.
THE STORMS TONIGHT DO APPEAR TO BE GOOD RAINMAKERS AS WELL. DEEP
MOISTURE WILL BE PRESENT THROUGH MUCH OF THE LOWER AND MIDDLE
TROPOSPHERE. A MAJORITY OF THE CAMS PRODUCE A BROAD SWATH OF
AROUND AN INCH OF RAIN THROUGH SATURDAY, WITH EMBEDDED NARROWER
STREAKS AROUND 3 INCHES POSSIBLE. MOST CAMS PLACE THE HIGHEST RAIN
POTENTIAL ALONG AND SOUTH OF I-96. SEE THE HYDROLOGY SECTION FOR
ADDITIONAL DETAILS GIVEN THE RECENT RAINY CONDITIONS.
TOWARD MIDDAY AND AFTERNOON SATURDAY, IT WILL REMAIN SHOWERY FOR
MANY AREAS, BUT DIMINISHING INSTABILITY WILL BE A LIMITING FACTOR
FOR THUNDERSTORM POTENTIAL. SOME OF THE CAMS INCLUDING THE HRRR
AND WRF-ARW DEPICT A NARROW COLD FRONTAL RAINBAND DEVELOPING WITH
25-35 MPH GUSTS IN ITS VICINITY.
- TURNING COLDER FROM SUNDAY TO TUESDAY
A TEMPORARY CHANGE IN THE PATTERN AS SYNOPTIC TROUGHING OVER THE
GREAT LAKES BRINGS -5 TO -10 C AIR AT 850 MB. THIS WILL SUPPORT
HIGHS ONLY THE 40S SUNDAY THROUGH TUESDAY, AND LOWS ARE FAVORED TO
DIP INTO THE 20S MONDAY NIGHT. SOME SNOW FLURRIES ARE POSSIBLE
SUNDAY MORNING, AND SNOW SHOWERS ARE ALSO POSSIBLE MONDAY AS
CLIPPER-STYLE SHORTWAVE TROUGHS MOVE THROUGH THE MEAN FLOW
PATTERN.
- RAINY PATTERN RETURNS LATTER HALF OF NEXT WEEK
AN ACTIVE SPRING PATTERN IS FAVORED TO RETURN LATER NEXT WEEK AND
INTO THE EARLY WEEK FOLLOWING, WITH WESTERN CONUS TROUGHING AND A
BERMUDA HIGH SETTING UP TO PROVIDE A FLOW OF WARMER AIR AND
MOISTURE FROM THE GULF AS EARLY AS THURSDAY. YESTERDAY'S CPC
OUTLOOK HIGHLIGHTED LOWER MICHIGAN IN A MODERATE CHANCE FOR HEAVY
PRECIPITATION DURING THIS UPCOMING PATTERN.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 206 AM EDT SAT APR 4 2026
A WARM FRONT IS SITUATED ACROSS PORTIONS OF CENTRAL INDIANA AND
ILLINOIS AT 06Z. A SURGE OF MOISTURE LIFTING OVER THE WARM FRONT
WILL PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS THE REMAINDER OF
THE NIGHT AND INTO THE DAYLIGHT MORNING HOURS OF SATURDAY. THE
INCREASE IN MOISTURE WILL ALSO LOWER CEILINGS FROM VFR IN MANY
AREAS AT PRESENT TO MVFR AND IFR AS WE WORK THROUGH THE REST OF
THE NIGHT AND INTO SATURDAY MORNING. THE COLD FRONT ASSOCIATED
WITH THE SYSTEM MOVING THROUGH THE GREAT LAKES REGION TODAY WILL
SWEEP EAST IN THE EARLY AFTERNOON AND AT THAT TIME, CEILINGS AND
VISIBILITIES WILL BEGIN TO IMPROVE A BIT. AFTER 00Z SATURDAY
EVENING WE WILL TREND TOWARDS VFR AS WE WILL BE WELL BEHIND THE
COLD FRONT.
IT WILL BE FAIRLY WINDY DURING THIS 24 HOUR PERIOD WITH GUSTY
EASTERLY WINDS THIS MORNING. THIS AFTERNOON AFTER 18Z, WINDS WILL
INCREASE FURTHER OUT OF THE WEST. LOOK FOR SPEEDS IN THE 15-25
KNOT RANGE WITH GUSTS TOWARDS 35 KNOTS.
MARINE
ISSUED AT 204 PM EDT FRI APR 3 2026
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER LAKE
MICHIGAN LATE THIS EVENING AND CONTINUE OVERNIGHT. A NEW SMALL
CRAFT ADVISORY WILL BE NEEDED LATE TONIGHT FOR STRENGTHENING EAST
WINDS, BECOMING SOUTHWEST DURING THE DAY SATURDAY, WITH WEST WINDS
PERSISTING INTO MUCH OF SUNDAY. WAVES WILL BUILD ON SATURDAY AND
DIMINISH LATE SUNDAY. ANOTHER PERIOD OF HAZARDOUS CONDITIONS ON
THE LAKE IS LIKELY MONDAY INTO TUESDAY.
HYDROLOGY
ISSUED AT 204 PM EDT FRI APR 3 2026
2 TO 4 INCHES OF RAIN HAS FALLEN ACROSS A LARGE PORTION OF LOWER
MICHIGAN OVER THE LAST WEEK. RIVERS ARE NOW RISING, AND SOILS ARE
SATURATED. A FINAL ROUND OF RAIN FROM THIS STORM CYCLE IS EXPECTED
TO IMPACT OUR AREA LATE FRIDAY NIGHT AND CONTINUE THROUGH THE DAY
SATURDAY. MOST AREAS WILL RECEIVE AN ADDITIONAL 0.5 TO 1.0 INCHES
OF RAIN, WITH SOME INDICATIONS THAT A FEW COUNTIES COULD END UP
WITH A STREAK OF MORE LIKE 1.5 TO 2.5 INCHES OF RAIN OR MORE. IF
THIS HEAVIER RAIN TRACKS OVER AN URBAN AREA LIKE KALAMAZOO, GRAND
RAPIDS, OR LANSING, LOCALIZED URBAN FLOODING ISSUES ARE LIKELY.
MEANWHILE, AS ALL THIS WATER CONTINUES TO FIND ITS WAY INTO OUR
RIVER SYSTEMS, MINOR FLOODING IS BECOMING LIKELY ON PARTS OF THE
MUSKEGON RIVER, AND IS ALSO A POSSIBILITY ON SOME OF THE TYPICAL
FLOOD-PRONE TROUBLE SPOTS IN THE GRAND RIVER WATERSHED, INCLUDING
IN COMSTOCK PARK AND MAPLE RIVER. MUCH WILL DEPEND ON EXACTLY
WHERE THE HEAVIEST SWATH OF THE UPCOMING RAIN FALLS, BUT THE
BOTTOM LINE IS THAT SOME MINOR RIVER FLOODING IS BECOMING MORE
LIKELY ACROSS PARTS OF SOUTHWEST AND WEST-CENTRAL MICHIGAN AS ALL
THIS RAIN CONTINUES TO ADD UP.
GRR WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT SUNDAY FOR LMZ844>849.
DISCUSSION...CAS
AVIATION...DUKE
MARINE...CAS
HYDROLOGY...AMD
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